AMOC: Crucial ocean currents are unlikely to shut down completely by the end of the century

Important ocean currents will rarely close by the end of this century, according to new findings that undermine the end of the impending catastrophic collapse.

The Atlantic Meridian Surrounding Circulation (AMOC) transports warm water from the tropical north and helps maintain temperatures in Northern Europe. The temperature and the influx of cold water from the Arctic ice weakens the current temperature, and scientists fear it can stop it completely. This will disrupt marine ecosystems and cool the European climate a few degrees faster.

Some researchers say that the irreversible closure of AMOC could be in the century. But I say this worst-case scenario is unlikely Jonathan Baker At the Met Office in the UK.

To investigate whether a complete AMOC collapse of this century is possible, Baker and his colleagues used 34 climate models to simulate changes in AMOC under extreme climate change, and greenhouse gas levels trained overnight from today's levels. The team also modeled a large amount of freshwater entering the North Atlantic at many times the rate of ice melting now.

They found that although AMOC is significantly weakened in these two scenarios, ocean currents continue in their weakened state, supported by deep-sea upwellings in the North Atlantic, driven by southern sea winds. “The Southern Ocean winds continue to blow, and this brings deep waters up to the surface. This works like a powerful pump,” Baker says. “This keeps AMOC running on models of this century.”

This finding helps explain why climate models generally simulate more stable AMOCs in the warming world compared to studies that rely on statistical methods. This tends to suggest that AMOC is more vulnerable.

Niklas Bore The Potsdam Climate Impact Institute in Germany said the findings are “good news” for those worried about the imminent collapse of the AMOC. “I agree that all cutting-edge climate models will not show a complete AMOC collapse within the 21st century.

However, the model does not predict a complete collapse of AMOC, but shows that quaternary reddish CO2 concentrations lead to a 20-81% reduction in the current intensity.

With AMOC weaker by about 50%, the impact on climate will become important, Baker says it will be important due to marine ecosystem disruption, sea level rise on the North Atlantic coastline, and changes in global rainfall patterns that affect crop harvests around the world. However, this type of weakening does not bring rapid cooling to Europe, he says.

In comparison, Bohr emphasizes that AMOC, which is 80% less than today, will have a devastating effect. “Of course, it's a nearly blocked AMOC,” he says. “It has all the impact on Europe's cooling and changing patterns of tropical monsoon, and all the things we are concerned about.”

Stephen RahmstoefHe is also at the Potsdam Institute for Climate Impact in Germany, and agrees that under the extreme warming of this century, there may be a weak and shallow AMOC trend left in the world. Some studies even define AMOC disintegration as this type of substantial weakening, he says. “A new study is investigating the remaining wind-driven covers [current] In more detail, this is a valuable contribution to the scientific literature,” he says. “However, in response to human-induced global warming, we will not change our assessment of the risks and impacts of future AMOC changes.”